1. Field of the Invention
The present invention relates in general to catalytic converters of a type having a catalyst-coated honeycomb grid, called a monolith, in the housing of the converter, and more particularly to structures for safely supporting the monolith in the housing. More specifically, the present invention is concerned with holders by which the monolith is resiliently and safely held in the housing.
2. Description of the Prior Art
In recent cars, a catalytic converter is installed in an exhaust system of the engine to reduce exhaust emissions. Usually, the converter has a heat-resistant metal housing in which a catalyst-coated honeycomb grid, called monolith, is held through resilient holders or the like.
One of such conventional catalytic converters is shown in Japanese Patent First Provisional Publication 7-317537, which uses wire mesh members as the resilient holders. That is, in the converter, a cylindrical structure made of wire mesh is installed between the monolith and housing to resiliently hold the monolith in a radial direction, and two annular washers made of wire mesh are disposed on front and rear ends of the monolith to resiliently hold the monolith in an axial direction. However, due to fragility inevitably possessed by the monolith, particularly by circular peripheral edges of the monolith, safety holding of the same in the housing has been very difficult even when the above-mentioned resilient holders are practically used.
It is therefore an object of the present invention to provide a monolith supporting structure for resiliently and safely supporting a monolith in a housing of the converter.
According to a first aspect of the present invention, there is provided a monolith supporting structure for use in a catalytic converter having a monolith held in a housing. The structure comprises an annular seat structure defined by the housing; and an annular resilient washer made of wire mesh, the washer being put on the annular seat structure for supporting thereon a circular peripheral edge of the monolith. The washer has a generally rectangular cross section and has a chamfered surface around a circular outer surface thereof. The chamfered surface is positioned radially outside the circular peripheral edge of the monolith.
According to a second aspect of the present invention, there is provided a monolith supporting structure for use in a catalytic converter having a monolith held in a housing. In this structure, the washer has a first surface put on the annular seat structure and a second surface for directly supporting thereon the circular peripheral edge of the monolith, and the washer has a generally rectangular cross section and has a chamfered surface around a circular inner surface thereof, so that a width of the second surface of the annular resilient washer is smaller than that of the first surface of the washer.
According to a third aspect of the present invention, there is provided a monolith supporting structure for use in a catalytic converter having a monolith held in a housing. In this structure, the washer comprises an outer portion located radially outside the circular peripheral edge of the monolith and an inner portion located radially inside the circular peripheral edge, and the outer portion of the washer produces no swelled portion, that would surround the circular peripheral edge, even when compressed by the monolith.
According to a fourth aspect of the present invention, there is provided a monolith supporting structure for use in a catalytic converter having a monolith held in a housing. In this structure, the washer has a generally rectangular cross section and has first and second chamfered surfaces around circular outer and inner surfaces thereof, so that a width of the second surface of the annular resilient washer is smaller than that of the first surface of the washer.